Fillings are a very common dental procedure but the material that dentists have traditionally used for fillings, amalgam, has fallen out of use. White composite filling materials which are indistinguishable from the tooth have taken the place of amalgam but they contain photoactive materials that must be hardened with light. The light cannot effectively penetrate the material so it must be applied and hardened in several steps. The Vienna University of Technology in collaboration with the company Ivoclar Vivadent have recently developed a new type of photoactive material based on germanium. The germanium component improves the photo-activity for a much quicker application process.
Modern dental composites are made up of a mixture of material components that include inorganic fillers as well as photoactive resins that solidify when exposed to light of a certain wavelength. Professor Robert Liska of the Vienna University of Technology (TU Vienna) has experience working with photoactive substances. The wavelength of the light used determines how far it will penetrate into the material. “Usually, light in the violet and ultraviolet region is used,” according to Liska. Light with longer wavelengths can be used to penetrate deeper into the composite material but this can disrupt the polymerization process and cause the procedure to be repeated.
A New Composite
The new composite materials based on germanium help solve the problem of poor light penetration to speed up the procedure. The germanium based molecule splits into two parts when exposed to blue light and creates radicals that initiate a chain reaction that assembles the other molecular compounds in the filling into polymers and hardens the material. The Vienna University of Technology created the germanium-based photo initiator which was tested by Ivoclar Vivadent. The germanium based photoactive material increases the hardening depth from 2 mm to 4 mm which makes the procedure much quicker and easier.
Success of New Compound
The success of the germanium based materials has led to the Vienna University of Technology and Ivoclar Vivadent expanding their collective research in dental materials. The Institute for Applied Synthetic Chemistry and the Institute for Materials Science and Technology opened a laboratory for developing “photopolymers in digital and restorative dentistry” with funding from Ivoclar Vivadent and Christian Doppler Research Association. Researchers within the laboratory work to develop photosensitive substances for dentistry and look into the potential of 3D printing for ceramic implants.